import type { CellKey, GridInventory, InventoryItem } from '../grid-inventory/types';
import type { GameItemMeta } from '../progress/types';
import { createRegion, createRegionAxis } from '@/core/region';
import type { GameCard, GameCardMeta, PlayerDeck, DeckRegions } from './types';

/**
 * Generates a unique card ID for a cell within an item.
 */
function generateCardId(itemId: string, cellIndex: number): string {
    return `card-${itemId}-${cellIndex}`;
}

/**
 * Collects all cell keys from an item's shape in a deterministic order.
 * Iterates the shape grid row by row, left to right, top to bottom.
 */
function getItemCells(item: InventoryItem<GameItemMeta>): CellKey[] {
    const cells: CellKey[] = [];
    const { shape, transform } = item;
    const { grid } = shape;
    const { offset, rotation, flipX, flipY } = transform;

    // Track local dimensions (may swap on rotation)
    let localWidth = grid[0]?.length || 1;
    let localHeight = grid.length;

    for (let gy = 0; gy < grid.length; gy++) {
        for (let gx = 0; gx < grid[gy].length; gx++) {
            if (!grid[gy][gx]) continue;

            // Start from grid coordinates
            let x = gx;
            let y = gy;

            // Apply rotation (90 degree increments, clockwise)
            const rotTimes = ((rotation % 4) + 4) % 4;
            for (let r = 0; r < rotTimes; r++) {
                const newX = localHeight - 1 - y;
                const newY = x;
                x = newX;
                y = newY;
                // Swap dimensions for next iteration
                const tmp = localWidth;
                localWidth = localHeight;
                localHeight = tmp;
            }

            // Reset local dimensions for fresh computation per cell
            localWidth = grid[0]?.length || 1;
            localHeight = grid.length;

            // Apply flips
            if (flipX) {
                x = -x;
            }
            if (flipY) {
                y = -y;
            }

            // Apply offset
            const finalX = x + offset.x;
            const finalY = y + offset.y;

            cells.push(`${finalX},${finalY}`);
        }
    }

    return cells;
}

/**
 * Creates a single card from an inventory item.
 *
 * @param itemId - The inventory item instance ID
 * @param itemData - The CSV item data
 * @param cellKey - The cell key ("x,y") this card represents
 * @param cellIndex - Index of the cell for unique ID generation
 */
function createItemCard(
    itemId: string,
    itemData: GameItemMeta['itemData'],
    cellKey: CellKey,
    cellIndex: number
): GameCard {
    const cardId = generateCardId(itemId, cellIndex);

    return {
        id: cardId,
        regionId: '',
        position: [],
        sourceItemId: itemId,
        itemData,
        cellKey,
        displayName: itemData.name,
        description: itemData.desc,
    };
}

/**
 * Creates a status card that does not correspond to any inventory item.
 * Status cards represent temporary effects like wounds, stuns, etc.
 *
 * @param id - Unique identifier for the card instance
 * @param displayName - Display name (e.g. "伤口", "眩晕")
 * @param description - Card description / ability text
 */
function createStatusCard(
    id: string,
    displayName: string,
    description: string
): GameCard {
    return {
        id,
        regionId: '',
        position: [],
        sourceItemId: null,
        itemData: null,
        cellKey: null,
        displayName,
        description,
    };
}

/**
 * Generates a complete player deck from the current inventory state.
 *
 * For each item in the inventory, N cards are generated where N is the
 * number of cells the item occupies (shape.count).
 *
 * All generated cards are placed in the draw pile initially.
 *
 * @param inventory - The player's grid inventory
 * @returns A PlayerDeck with all cards in the draw pile
 */
function generateDeckFromInventory(inventory: GridInventory<GameItemMeta>): PlayerDeck {
    const cards: Record<string, GameCard> = {};
    const drawPile: string[] = [];

    for (const item of inventory.items.values()) {
        const itemData = item.meta?.itemData;
        if (!itemData) continue;

        // Generate one card per occupied cell in the item's shape
        const cellCount = item.shape.count;
        const cells = getItemCells(item);

        for (let i = 0; i < cellCount; i++) {
            const cellKey = cells[i] ?? `${i},0`;
            const card = createItemCard(item.id, itemData, cellKey, i);
            cards[card.id] = card;
            drawPile.push(card.id);
        }
    }

    return {
        cards,
        drawPile,
        hand: [],
        discardPile: [],
        exhaustPile: [],
    };
}

/**
 * Creates region definitions for deck management.
 * Returns regions for draw pile, hand, discard pile, and exhaust pile.
 */
function createDeckRegions(): DeckRegions {
    return {
        drawPile: createRegion('drawPile', [
            createRegionAxis('index', 0, 0), // unbounded
        ]),
        hand: createRegion('hand', [
            createRegionAxis('index', 0, 0),
        ]),
        discardPile: createRegion('discardPile', [
            createRegionAxis('index', 0, 0),
        ]),
        exhaustPile: createRegion('exhaustPile', [
            createRegionAxis('index', 0, 0),
        ]),
    };
}

/**
 * Creates an empty player deck structure.
 */
function createPlayerDeck(): PlayerDeck {
    return {
        cards: {},
        drawPile: [],
        hand: [],
        discardPile: [],
        exhaustPile: [],
    };
}

export {
    generateDeckFromInventory,
    createStatusCard,
    createDeckRegions,
    createPlayerDeck,
    generateCardId,
};